Systems and methods for single-phase fluid sampling

ABSTRACT

An assembly capable of being disposed in a subterranean bore for obtaining a fluid sample is described. The assembly can include an apparatus having a sample chamber and a housing encasing the sample chamber and providing a pressure source. The pressure source can be disposed of in an annulus defined by the sample chamber and the housing. The assembly can be attached to a slick line or wire line and conveyed into a wellbore.

TECHNICAL FIELD OF INVENTION

The present invention relates generally to testing and evaluation ofsubterranean formation fluids and, in particular (but not necessarilyexclusively) to, a single-phase fluid sampling apparatus for obtaining afluid sample and maintaining the sample near reservoir pressure.

BACKGROUND

It is well known in the subterranean well drilling and completion art toperform tests on formations intersected by a wellbore. Such tests aretypically performed to determine geological or other physical propertiesof the formation and fluids provided thereform. For example, parameterssuch as permeability, porosity, fluid resistivity, temperature,pressure, and bubble point may be determined. These and othercharacteristics of the formation and fluid may be determined byperforming tests on the formation before the well is completed.

One type of testing procedure that is commonly performed is to obtain afluid sample from the formation to, among other things, determine thecomposition of the formation fluids. In this procedure, it is importantto obtain a sample of the formation fluid that is representative of thefluid as it exists in the downhole environment. In some typical samplingprocedures, a sample of the fluid may be obtained by lowering a samplingtool having a sampling chamber into the wellbore on a conveyance such asa wireline, slickline, coiled tubing, jointed tubing or the like. Whenthe sampling tool reaches the desired depth, one or more ports areopened to allow collection of the formation fluids. The ports may beactuated in variety of ways such as by electrical, hydraulic ormechanical methods. Once the ports are opened, formation fluids travelthrough the ports and a sample of the formation fluids is collectedwithin the sampling chamber of the sampling tool. After the sample hasbeen collected, the sampling tool may be withdrawn from the wellbore sothat the formation fluid sample may be analyzed.

It has been found, however, that as the fluid sample is retrieved to thesurface, the temperature of the fluid sample decreases causing shrinkageof the fluid sample and a reduction in the pressure of the fluid sample.Once such a process occurs, the resulting fluid sample may no longer berepresentative of the fluids present in the formation. Therefore, a needhas arisen for an apparatus and method for obtaining a fluid sample froma formation without degradation of the sample during retrieval of thesampling tool from the wellbore. A need has also arisen for such anapparatus and method that are capable of being conveyed via a slickline,wireline, or coiled tubing.

SUMMARY

Certain embodiments described herein are directed to apparatuses,systems, and methods for obtaining a fluid sample in a subterraneanwell. The apparatuses, systems, and methods can be disposed in a bore ofa subterranean formation.

In one aspect, an apparatus can include a sampler and a housing. Thesampler can have a sample chamber configured for being selectively influid communication with an exterior of the sampler. The sample chambercan receive at least a portion of a fluid sample. The housing can bedisposed exterior to the sampler. An annulus can be defined between atleast part of the housing and at least part of the sampler. The annuluscan include a compressible fluid.

In at least one embodiment, the apparatus can be capable of beingdisposed in a subterranean well using at least one of a slickline,wireline, or coiled tubing.

In at least one embodiment, the compressible fluid can be nitrogen.

In at least one embodiment, the annulus can be selectively in fluidcommunication with the sample chamber. In such embodiments, thecompressible fluid can be operable to pressurize the fluid samplereceived in the sample chamber.

In at least one embodiment, the apparatus can include a manifold. Themanifold can facilitate fluid communication between the sampling chamberand the annulus.

In at least one embodiment, the housing can encase at least a portion ofthe sample.

In at least one embodiment, the housing can extend longitudinally alongthe length of the sampler.

In at least one embodiment, the housing can be positioned generallycoaxially with the sampler.

In at least one embodiment, the annulus can have a volume. The volume ofthe annulus can be sufficient to include a volume of the compressiblefluid to pressurize the fluid sample received in the sample chamber.

In at least one embodiment, the apparatus further includes a trigger.The trigger can cause or initiate the apparatus to obtain the fluidsample.

In at least one embodiment, the apparatus further includes a triggersleeve. The trigger sleeve can be disposed exterior to the trigger andprovide protection to the trigger from an environment exterior to thetrigger.

In another aspect, a method for obtaining a fluid sample in asubterranean well is provided. The method includes positioning a fluidsampler in the well by at least one of a slickline, wireline, or coiledtubing; obtaining a fluid sample in a sample chamber of the fluidsampler; and pressurizing the fluid sample using a pressure sourcedisposed in an annulus. The annulus can be defined by a housing encasingthe fluid sampler. The pressure source can be in fluid communicationwith the sample chamber.

In at least one embodiment, the annulus can be defined by an innerdiameter of the housing and an outer diameter of the fluid sampler.

In at least one embodiment, the annulus can extend longitudinally alongthe length of the sampler.

In at least one embodiment, the pressure source can be a compressiblefluid.

In at least one embodiment, the compressible fluid can be nitrogen.

In at least one embodiment, the method further includes retrieving thefluid sampler to the surface.

In yet another aspect, a system for obtaining a fluid sample in asubterranean well is provided. The system can be disposed with a leastone of a slickline, wireline, or coiled tubing. The system includes asampler, a housing, and a pressure source comprising a compressiblefluid. The sampler can receive a sample of hydrocarbon fluid in a samplechamber. The housing can be disposed exterior to an outer diameter ofthe sampler. The pressure source can be disposed within an annulusdefined by the outer diameter of the sampler and an inner diameter ofthe housing. The housing can be configured to provide a pressure sealbetween the annulus and an environment exterior to the housing. Thesampler can be configured to be selectively in fluid communication withthe pressure source such that the compressible fluid is operable topressurize the sample of hydrocarbon fluid.

In at least one embodiment, the system can include a valving assemblyconfigured to permit pressure from the pressure source to be applied tothe sampler.

In at least one embodiment, the system can include a trigger configuredto cause the sampler to obtain the hydrocarbon fluid.

These illustrative aspects and embodiments are mentioned not to limit ordefine the invention, but to provide examples to aid understanding ofthe inventive concepts disclosed in this application. Other aspects,advantages, and features of the present invention will become apparentafter review of the entire application.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic illustration of a well system having a fluidsampler apparatus according to one embodiment of the present invention.

FIG. 2 is a cross-sectional view of a fluid sampler apparatus having asampler and housing according to one embodiment of the presentinvention.

FIGS. 3A-E are cross-sectional views of successive axial portions of afluid sampler apparatus according to one embodiment of the presentinvention.

DETAILED DESCRIPTION

Certain aspects and embodiments of the present invention relate tosystems and assemblies that are capable of being disposed in a bore,such as a wellbore, in a subterranean formation for use in producinghydrocarbon fluids from the formation. In some embodiments, theassemblies and devices can include an apparatus for obtaining a fluidsample produced from a subterranean formation and maintaining the fluidsample near a reservoir pressure at which the fluid sample was obtained.In some embodiments, the assemblies and devices can be attached to aslickline, wireline, or coiled tubing and conveyed into a wellbore.

Described herein are devices and assemblies that comprise a samplerhaving a sample chamber and a housing encasing the sample chamber.Further, the devices and assemblies can comprise a pressure source. Thepressure source can be disposed within an annulus defined by the innerdiameter of the housing and the outer diameter of the sampler. In someembodiments, the housing and the sampler can be coaxial, have generallythe same cylindrical axis, or have a generally concentric relationshipsuch that the housing encases or surrounds the sampler.

Conventional sampling devices often rely on a separate, common nitrogencase to pressurize a fluid sample. In such devices, the nitrogen case isserially attached to the sampler device. It is desirable to minimize thenumber of devices, and in turn the resulting total length of devicesconveyed downhole, when obtaining a sample from a formation. Someembodiments of the present invention described herein can increase thewidth of the fluid sampler system and minimize the length of the samplersystem.

The housing can extend longitudinally along at least a portion of thesampler such that the annulus comprises a sufficient volume to house apressure source for pressurizing the fluid sample. In some embodiments,the housing has a length greater than the sample chamber to provide alarger volume. The inner diameter of the housing may be modified toincrease the volume of the annulus.

The pressure source can include a compressible fluid. In someembodiments, the compressible fluid is nitrogen. The compressed nitrogencan be disposed in the housing at between about 7,000 psi to about15,000 psi. In other embodiments, other fluids or combination of fluidsand/or other pressures both higher and lower can be used.

In some embodiments, the housing can provide a pressure seal to preventthe unintended release of the compressible fluid. For example, a Teflon®ring can be employed to provide a seal to prevent the unintended releaseof the compressible fluid from the apparatus.

Fluid sampler apparatuses according to some embodiments can be conveyedinto the wellbore via a slickline, wireline, or coiled tubing.

A fluid sampler apparatus may include a trigger. In some embodiments,for example in a slickline application, a battery-powered or mechanicaltimer type device can be utilized to initiate the sampling process. Anaccelerometer may be employed that can initiate the sampling processonce the apparatus has been stationary for a certain period of time. Inother embodiments, for example in a wireline application, a signal canbe sent via the wireline to turn on a motor or other like device tobegin the sampling process by opening a valve.

At the position at which a sample is obtained within a wellbore, thesample is exposed to a certain pressure and environment conditionsassociated with the wellbore environment. According to certainembodiments of the present invention described herein, the nitrogensource, or other compressible fluid, can be used to pressurize thesample. In some embodiments, the nitrogen source can be located in ahousing surrounding the sampler, rather than a separate, discretecomponent characteristic of conventional samplers.

The illustrative examples are given to introduce the reader to thegeneral subject matter discussed herein and not intended to limit thescope of the disclosed concepts. The following sections describe variousadditional embodiments and examples with reference to the drawings inwhich like numerals indicate like elements and directional descriptionare used to describe illustrative embodiments but, like the illustrativeembodiments, should not be used to limit the present invention.

FIG. 1 shows a well system 10 comprising a fluid sampler apparatus 18according to one embodiment. A tubular string 14 is positioned in awellbore 12 extending through various earth strata 20. An internal flowpassage 15 extends longitudinally through the tubular string 14.

The fluid sampler apparatus 18 is attached to a slickline 16. A spool 17provides a structure upon which the slickline 16 can be wound andconveyed. In other embodiments, the fluid sampler apparatus 18 can beconveyed using a wireline, coiled tubing, downhole robot, or the like.Although wellbore 12 is shown as being cased and cemented, it canalternatively be uncased or open hole.

Even though FIG. 1 depicts a vertical well, it should be noted thatembodiments of the fluid sampler apparatus 18 of the present inventioncan be used in deviated wells, inclined wells, or horizontal wells. Assuch, the use of directional terms such as above, below, upper, lower,upward, downward, and the like are used in relation to the illustrativeembodiments and as they are depicted in the figures. In general, above,upper, upward, and similar terms refer to a direction toward the earth'ssurface along a well bore and below, lower, downward and similar termsrefer to a direction away from the earth's surface along the wellbore.

As described in more detail below, the fluid sampler apparatus 18 canobtain a fluid sample from the formation at a certain position withinthe wellbore. The position at which a fluid sample is obtainedexperiences certain environment conditions, for example a certainreservoir pressure. According to some embodiments described herein, thefluid sampler apparatus can maintain the fluid sample at or near thereservoir pressure (or other condition) at which the fluid sample wasobtained.

Referring to FIG. 2, a fluid sampler apparatus 18 having a sampler 30and a housing 34 is shown. The housing 34 can be a high-pressure outershell that encases at least a portion of the sampler 30. In someembodiments, the housing 34 encases the entire sampler 30. In otherembodiments, the housing 34 can encase a portion of the sampler. Thesampler 30 can include a sample chamber 32 and additional components,such as valves, pistons, metering devices, and other componentsdescribed in more detail below in connection with FIGS. 3A-3E, tofacilitate obtaining a fluid sample.

An annulus 35 is shown as the area between the sampler 32 and thehousing 34. As the sampler 32 and the housing 34 are generally coaxialor concentric, the annulus 35 is defined by the area between an innerdiameter of the housing 34 and an outer diameter of the sampler 32.Within the annulus 35 is a compressible fluid, for example nitrogen.

The sample chamber 32 is in fluid communication with the annulus 35. Thenitrogen-filled annulus 35 can provide a pressure source to pressurize afluid sample for the apparatus after the fluid sample is obtained. Asthe nitrogen is in close proximity to the sample chamber, a valve ormanifold 38 can provide a channel and/or facilitate the nitrogenentering into the sampler to maintain the pressure conditions at whichthe fluid sample is obtained.

The housing 34 may be a sufficiently rigid material to withstand thepressures experienced in downhole conditions. In some embodiments, thehousing 34 is made of steel.

The housing 34 provides a structure to protect the sampler from theenvironmental or reservoir conditions experienced within a wellbore. Insome embodiments, the nitrogen-filled annulus 35 can provide additionalsupport of the housing 34 as the fluid sample apparatus is conveyeddownhole where higher pressure conditions are experienced.

Referring now to FIGS. 3A-3E, a fluid sampling apparatus 100 having ahousing 181 encasing a sampler that embodies principles of the presentinvention is shown. The housing 181 spans the longitudinal length of thesampler. An annulus 182 is defined by the inner diameter of the housing181 and the sampler casing 102. A pressure source, such as acompressible fluid, is disposed with the annulus 182. The annulus 182can include a volume to provide a sufficient amount of compressiblefluid capable of pressurizing a fluid sample received in the sampler100. The length of the housing 181 and/or the inner diameter of thehousing 181 can be modified to increase or decrease the volume of theannulus 182, as appropriate.

A passage 110 can be formed in an upper portion of fluid samplingapparatus 100 (see FIG. 3A). The passage 110 in the upper portion of thefluid sampling apparatus 100 can be in communication with a samplechamber 114 via a check valve 116. The check valve 116 permits fluid toflow from the passage 110 into the sample chamber 114, but preventsfluid from being released from the sample chamber 114 to the passage110.

A debris trap piston 118 can be disposed within the sampler casing 102and can separate the sample chamber 114 from a metering fluid chamber120. When a fluid sample is received in the sample chamber 114, thedebris trap piston 118 can be displaced downwardly relative to thesampler casing 102 to expand the sample chamber 114.

Prior to such downward displacement of the debris trap piston 118,however, fluid flows through the sample chamber 114 and a passageway 122of the piston 118 into the debris chamber 126 of the debris trap piston118. The fluid received in the debris chamber 126 can be prevented fromflowing back into the sample chamber 114 due to the relativecross-sectional areas of the passageway 122 and the debris chamber 126,as well as the pressure maintained on the debris chamber 126 from thesample chamber 114 via the passageway 122. An optional check valve (notshown) may be disposed within the passageway 122, if desired.

In this manner, the fluid initially received into the sample chamber 114can be trapped in the debris chamber 126. The debris chamber 126 thuspermits this initially received fluid to be isolated from the fluidsample later received in the sample chamber 114. In some embodiments,the debris trap piston 118 can include a magnetic locator that can beused as a reference to determine the level of displacement of the debristrap piston 118 and thus the volume of the collected sample within thesample chamber 114 after a sample has been obtained.

A metering fluid chamber 120 initially contains a metering fluid, suchas a hydraulic fluid, silicone oil, or like material. A flow restrictor134 and a check valve 136 can control flow between the chamber 120 andan atmospheric chamber 138 that initially contains a gas at a relativelylow pressure, for example, air at atmospheric pressure. A collapsiblepiston assembly 140 includes a prong 142 that initially maintains acheck valve 144 in an “off seat” position so that flow in bothdirections can be permitted through the check valve 144 between thechamber 120 and the chamber 138.

In some embodiments, when elevated pressure is applied to the chamber138, however, as described more fully below, the piston assembly 140 cancollapse axially, and the prong 142 no longer maintains the check valve144 “off seat”, thereby preventing flow from the chamber 120 to thechamber 138.

A piston 146 disposed within the sampler casing 102 separates thechamber 138 from a longitudinally extending atmospheric chamber 148 thatinitially contains a gas at a relatively low pressure such as air atatmospheric pressure. The piston 146 can include a magnetic locator usedas a reference to determine the level of displacement of the piston 146and thus the volume within the chamber 138 after a sample has beenobtained.

The piston 146 includes a piercing assembly 150 at its lower end. In theillustrated embodiment, the piercing assembly 150 is coupled to piston146 that creates a compression connection between a piercing assemblybody 152 and a needle 154. The needle 154 may be coupled to the piercingassembly body 152 via threading, welding, friction or other suitabletechnique. The needle 154 may have a sharp point at a lower end and mayhave a smooth outer surface. In other embodiments, the outer surface isfluted, channeled, knurled or otherwise irregular. In some embodimentsand as discussed more fully below, the needle 154 is used to actuate thepressure delivery subsystem of the fluid sampler when the piston 146 issufficiently displaced relative to the sampler casing 102.

Below the atmospheric chamber 148 and disposed within the longitudinalpassageway of the sampler casing 102 is a valving assembly 156. Thevalving assembly 156 can include a pressure disk holder that receives apressure disk therein that is depicted as rupture disk 360. In otherembodiments, other types of pressure disks that provide a seal, such asa metal-to-metal seal, with pressure disk holder 158 can be used,including a pressure membrane or other piercable member. Rupture disk160 can be held within pressure disk holder by a hold down ring 162 anda gland 164 that can be threadably coupled to the pressure disk holder.The valving assembly 156 also includes a check valve 166. The valvingassembly 156 initially prevents fluid communication between chamber 148and a passage 180 in a lower portion of sampling chamber 100. Afteractuation of the pressure delivery subsystem by the needle 154, thecheck valve 166 permits fluid flow from the passage 180 to the chamber148, but prevents fluid flow from the chamber 148 to the passage 180.

Passage 180 in the lower portion of sampling chamber 100 can beconfigured in sealed communication with the annulus 182 that includesthe pressure source. The compressible fluid stored within the annulus182 can flow from the passage 180 to the chamber 148, thus pressurizingthe sample.

As described above, once the fluid sampler is in its operableconfiguration and is located at the desired position within thewellbore, a fluid sample can be obtained into the sample chamber 114 bya trigger device of an operating actuator. Fluid from a passage can thenenter the passage 110 in the upper portion of the sampling chamber 100.The fluid flows from the passage 110 through the check valve 116 to thesample chamber 114. In some embodiments, the check valve 116 includes arestrictor pin 168 to prevent excessive travel of a ball member 170.

An initial volume of the fluid can be trapped in the debris chamber 126of piston 118 as described above. Downward displacement of the piston118 can be slowed by the metering fluid in the chamber 120 flowingthrough the restrictor 134. This can prevent pressure in the fluidsample received in the sample chamber 114 from dropping below its bubblepoint.

As the piston 118 displaces downward, the metering fluid in the chamber120 can flow through the restrictor 134 into the chamber 138. At thispoint, the prong 142 can maintain the check valve 144 in an “off seat”position. The metering fluid received in the chamber 138 can cause thepiston 146 to displace downwardly. When the needle 154 pierces therupture disk 160, the valving assembly 156 is actuated. Actuation of thevalving assembly 156 permits pressure from the pressure source storedwithin the annulus 182 to be applied to the chamber 148. Once therupture disk 160 is pierced, the pressure from the pressure sourcewithin the annulus 182 passes through the valving assembly 156,including moving the check valve 166 “off seat”. In the illustratedembodiment, a restrictor pin 174 prevents excessive travel of the checkvalve 166. Pressurization of the chamber 148 also results in pressurebeing applied to the chamber 138, and chamber 120 and thus to samplechamber 114.

The check valve 144 then prevents pressure from escaping from thechamber 120 and the sample chamber 114. The check valve 116 alsoprevents escape of pressure from sample chamber 114. In this manner, thefluid sample received in the sample chamber 114 is pressurized.

Fluid sampler apparatuses, such as those shown in the Figures, can beuseful for providing a sampler that can be conveyed via a slickline,wireline, or coiled tubing, rather than many conventional samplers thatare pipe conveyed. The apparatuses and devices described herein includea presence of a high-pressure source within the construction of theapparatus or device.

In the apparatuses and devices described herein, the pressure source isself-contained within each sampler, rather than a common pressure sourceas found in conventional sampling devices. In slickline, wireline, orcoiled tubing applications, a large, common pressure source casing isnot applicable.

The foregoing description of the embodiments, including illustratedembodiments, of the invention has been presented for the purpose ofillustration and description and is not intended to be exhaustive or tolimit the invention to the precise forms disclosed. Numerousmodifications, adaptations, and uses thereof will be apparent to thoseskilled in the art without departing from the scope of this invention.

What is claimed is:
 1. An apparatus for obtaining a fluid sample in asubterranean well, the apparatus comprising: a sampler having a samplechamber configured for being selectively in fluid communication with anexterior of the sampler and operable to receive at least a portion of afluid sample; a housing disposed exterior to the sampler, the housingdefining an annulus between at least part of the housing and at leastpart of the sampler, wherein the annulus comprises a compressible fluid.2. The apparatus of claim 1, wherein the apparatus is capable of beingdisposed in the subterranean well using at least one of a slickline,wireline, or coiled tubing.
 3. The apparatus of claim 1, wherein thecompressible fluid comprises nitrogen.
 4. The apparatus of claim 1,wherein the annulus is selectively in fluid communication with thesample chamber such that the compressible fluid is operable topressurize the fluid sample received in the sample chamber.
 5. Theapparatus of claim 1, further comprising a manifold configured toprovide the fluid communication between the sampling chamber and theannulus.
 6. The apparatus of claim 1, wherein the housing encases atleast a portion of the sampler.
 7. The apparatus of claim 1, wherein theannulus comprises a volume sufficient to contain a volume of thecompressible fluid to pressurize the fluid sample received in the samplechamber.
 8. The apparatus of claim 1, wherein the housing extendslongitudinally along the length of the sampler.
 9. The apparatus ofclaim 1, wherein the housing is generally coaxial with the sampler. 10.The apparatus of claim 1, wherein the compressible fluid has a greatercompressibility than hydraulic fluid.
 11. A method for obtaining a fluidsample in a subterranean well, the method comprising: positioning afluid sampler in the well by at least one of a slickline, wireline, orcoiled tubing; obtaining a fluid sample in a sample chamber of the fluidsampler; and pressurizing the fluid sample using a pressure sourcedisposed in an annulus defined by a housing encasing the fluid sampler,the pressure source being in fluid communication with the sample chamberand including a compressible fluid in the annulus.
 12. The method ofclaim 11, wherein the annulus is defined by an inner diameter of thehousing and an outer diameter of the sampler.
 13. The method of claim11, wherein the annulus extends longitudinally along the length of thesampler.
 14. The method of claim 11, wherein the compressible fluidcomprises nitrogen.
 15. The method of claim 11, further comprisingretrieving the fluid sampler to the surface.
 16. The method of claim 11,wherein positioning the fluid sampler in the well by at least one of theslickline, wireline, or coiled tubing includes positioning the fluidsampler in the well by wireline.
 17. The method of claim 11, furthercomprising running from a surface of the well the fluid samplerincluding the pressure source including the compressible fluid that isreleased into the annulus encasing the fluid sampler in the well.
 18. Asystem capable of being disposed with at least one of a slickline,wireline, or coiled tubing for obtaining a fluid sample in asubterranean well, the system comprising: a sampler for receiving asample of hydrocarbon fluid in a sample chamber, the sampler having anouter diameter; a housing disposed exterior to the outer diameter of thesampler, the housing having an inner diameter; and a pressure sourcecomprising a compressible fluid, the pressure source disposed within anannulus defined by the outer diameter of the sampler and the innerdiameter of the housing such that the compressible fluid is releasablein the annulus, wherein the housing is configured for providing apressure seal between the annulus and an environment exterior to thehousing, and wherein the sampler is configured for being selectively influid communication with the pressure source such that the compressiblefluid is operable to pressurize the sample of hydrocarbon fluid.
 19. Thesystem of claim 18, wherein the sampler comprises a valving assemblyconfigured to permit pressure from the pressure source to be applied tothe sampler.
 20. The system of claim 18, further comprising a triggerconfigured for causing the sampler to obtain the hydrocarbon fluid.